We have a network with a Catalyst 500 switch and a 871 Ethernet router. The router has been configured ,with SDM, a SDM default medium security firewall. We observe that there is continuous traffic between the router and the internet(DSL modem). I don't see this traffic on any of the hosts. The firewall is moderately active filtering incoming traffic, but the logging that I have been able to set up does not show the activity that I see on the router and modem front panels. Could this be an indication that the router is infected?